1. Field of the Invention
The present invention relates to a field of television, more particularly to a video signal processing apparatus for a wide-aspect television.
2. Prior Arts
Recently, a television set is gradually getting larger in size and a display format ratio is gradually expanded from a 4:3 display format ratio to a wide-aspect display format ratio of 16:9 or to a zoom display ratio. However, since broadcasting stations are still transmitting a television signal corresponding to a 4:3 display as usual, such television signal should be converted to a signal for producing a wide-aspect display or a zoom display. In general, in a wide-aspect television set, "an expanded picture" or a "wide aspect picture" means a 16:9 picture produced from a video signal representative of 4:3 display format ratio, and "a compressed picture" means a picture smaller than a 16:9 picture but larger than a 4:3 picture, which are shown in (A) and (B) of FIG. 2. U.S. Pat. No. 5,311,309 granted to Nathaniel H. Ersoz, et al, discloses a video signal processing apparatus for a wide-aspect television for processing a composite video signal to produce a 16:9 display or a zoom display.
FIG. 1 is a schematic block diagram of a conventional video signal processing apparatus for a wide-aspect television shown in above U.S. Patent. The functions of the apparatus disclosed therein are determined by an interpolator 337 and a timing generator 320/339. In particular, as can be anticipated in the functions of interpolator 337, the apparatus disclosed in the above U.S. Patent, has a main function for switching a 4:3 display to a 16:9 display or vice versa in addition to PIP (picture in picture) display function.
In such apparatus, there exist drawbacks in that reality is deteriorated when a 16:9 display is produced using the signal representative of a 4:3 display and the picture is expanded horizontally as shown in (A) of FIG. 2. Further, the picture should be cut in order to maintain the reality when a zoom display is produced from a signal representative of a 4:3 display, as shown in (B) of FIG. 2.